As Donald J. Trump ascended the steps of the US Capitol on Friday morning in anticipation of taking the oath of office and becoming the 45th president of the United States, protestors locked themselves arm-to-arm, forming human blockades of several entrances into the inauguration grounds.

Others marched through downtown Washington, smashing windows, setting cars alight, and clashing with lines of police, who used pepper spray and concussion grenades to clear intersections and contain the demonstrators.

The actions mark the beginning of what will be two days of mass protest in Washington — as well as across the country and the world — against the newly inaugurated Trump administration and represent what might be the dawn of a significant uptick in public opposition to the president's agenda.

A frequent refrain among media pundits, elected officials, and some academics says protests allow the public a moment of cathartic release — a chance to blow off some bottled-up frustration — but yield little, if anything, in the way of real world change.

Not so fast, according to Daniel Q. Gillion, an associate professor of political science at the University of Pennsylvania.

In a 2012 paper published in the Journal of Politics, Gillion argues that public protests held on the local level served as cues for public politicians of constituent unrest, which led to discernible shifts in how they voted in Congress.

Gillion was concerned specifically with political campaigns that sought to improve conditions for minority communities and how their efforts were reflected in roll-call votes in the US House of Representatives between 1961 and 1995.

"The district-level cues reflect a direct link between citizens' political preferences and congressional leaders' votes," he wrote. "The occurrence of one minority protest event is unlikely to have any influence on government behavior. But as the information provided through citizen's protest behavior accumulates, so does the impact it has on Congress."

Public protests influenced representatives of both political parties. Republican members of the House, Gillion found, became four percent more supportive and Democrats became eight percent more liberal in response to frequent demonstrations.

"There is a common notion that congressional representatives who are elected from heavily populated majority-minority districts do all that they can to address minority issues, regardless of whether protest actions are occurring in their districts," Gillion wrote. "This simply is not true."

Public protest, in other words, pushed even a sympathetic elected official to agitate more aggressively for action on civil rights issues. When people take to the streets, their actions are often described as a perversion or failure of democratic processes. But Gillion sees public protest as crucial to holding public officials accountable, especially on the local level where politicians are most vulnerable to constituent sentiments.

"Citizens are sometimes moved by events and political disappointments in ways that cannot be measured by the passivity of public opinion polls or delayed for an election cycle," he wrote. "In such events, people are compelled to act, and political protest is the avenue through which they can express their most urgent concerns. In doing so, their protest behavior becomes another vehicle by which they communicate to the government."

But, there's a current, albeit less academic, indicator that elected officials are acutely aware of the impact of public protest.

Republican legislatures in five states have offered proposals to ban them, according to an article in The Intercept. If passed, the bills could lead to heavy fines and even long prison terms for anyone who participates in non-violent civil disobedience, as many people have done recently in response to police shootings and the construction of fossil fuel infrastructure, like the Dakota Access Pipeline.

In North Dakota, for example, Republicans seek to allow motorists to run over protesters blocking a highway — a potentially lethal action — as long as it was done accidentally.

"This trend of anti-protest legislation dressed up as 'obstruction' bills is deeply troubling," Lee Rowland, a senior staff attorney at the American Civil Liberties Union, told the Intercept. "A law that would allow the state to charge a protester $10,000 for stepping in the wrong place, or encourage a driver to get away with manslaughter because the victim was protesting, is about one thing: chilling protest."